The present invention relates to automatic exposure time control circuits for cameras and, more particularly, to such circuits that are capable of selective automatic or manual exposure control.
In the field to which the invention relates, there are known exposure time control circuits for cameras which include a light measuring circuit having a photoelectric element, a shutter control circuit responsive to the output of the light measuring circuit, means for setting at least the value of film sensitivity for automatic exposure time control, means for manually setting the shutter speed with manual exposure time control, and switching means for alternatively selecting either automatic or manual exposure time control. However, such known circuitry requires two variable resistors. For example, a first variable resistor provides a signal in accordance with the film sensitivity and diaphragm aperture setting and is included in the light measuring circuit. A second variable resistor provides a signal representative of the manual shutter speed setting and is included in the shutter control circuit as shown, for example, in U.S. Pat. No. 3,728,946.